Gas discharge lamps are widely used to illuminate relatively large areas and are actually preferred over incandescent lights in many situations for various reasons. Gas discharge lamps provide the benefit of providing equal or better illumination intensity using relatively less energy than the alternative incandescent lights. These energy efficient lamps are highly beneficial in geographic locations having a reduced power supply and in areas where cost benefits are realized by reducing energy consumption.
Although gas discharge lamps are generally more energy efficient than incandescent lamps, in large scale uses the lamps still consume significant amounts of power. Additionally, in many cases the illumination intensity generated by the lamps is actually more than necessary for a given situation. For example, in a large warehouse environments having skylights and other windows, natural daylight may actually provide most of the necessary illumination such that the gas discharge lamps actually produce supplemental and possibly unnecessary or excess light. Of course, on cloudy days and at night the gas discharge lamps provide the majority if not all the illumination required within the warehouse environment. During those times that the lamps are producing unnecessary light, the lamps are also consuming unnecessary power. Ideally, the lamps could be controlled to deliver sufficient illumination, depending on the availability of natural light, while consuming minimal power.
In many cases, the consumption of energy by the gas discharge lamps is directly related to the illumination intensity level produced by the lamps. During times when the lamps produce a relatively bright illumination intensity, a relatively higher level of the energy is typically consumed by the lamp.
Setting or controlling the circuit to deliver the proper amount of power to the lamp under variable conditions has typically required the use of a manual-type control mechanism. Such a manual control mechanism may be either a slide switch or a knob. Each of these mechanisms allow for the variable control of the illumination intensity but unfortunately also require that an operator physically manipulate the devices in order to vary the illumination intensity. This type of control is unsatisfactory in conditions where the light entering through the windows is constantly varying since the operator must continuously take the time to adjust the illumination intensity in accordance with the varying light conditions. Hence on intermittently cloudy days or at dusk the operator is continuously interrupted to adjust the illumination intensity.
Moreover, implementing a manual-type control switch introduces the possibility that the person operating the switch may incorrectly determine whether the lamp is generating the proper or optimal illumination intensity for a given situation. Manually adjusted control systems are also difficult to set since many lamps may need to be adjusted to various independent levels based on the location of the windows in the building. For instance, the lamps located far from windows or skylights most likely should be adjusted to provide more illumination than those lamps located near a window or skylight. Unfortunately, the typical control switch controls many of these lamps from one location so that the operator does not have to walk to many different locations to adjust the lights. However, this location may be relatively far from some of the lamps which decreases a person's ability to accurately detect whether the illumination intensity produced by each particular lamp is satisfactory, let alone optimal. Indeed, the operator can only guess the proper illumination intensity for each of the different zones illuminated by the various lamps.
In order to overcome these drawbacks, gas discharge lamps are generally operated at higher-than-necessary intensity levels based on worst-case scenarios. For example, on intermittent cloudy days, the lamps are generally set to provide sufficient illumination based on times when the cloud cover blocks most natural light. The result is that more illumination than necessary is generated during periods of time when the clouds have dissipated which results in unnecessary energy consumption.
It is with respect to these considerations and others that the present invention has been made.